MSP430学习笔记1-I/O端口

开发版型号：SEED—MSP430F5529A

开发工具   ：CCS 5.4v

以下内容是CCS中I/O端口操作的一些简单的demo，现整理如下：

有关MSP430F5529芯片I/O口相关资料，可参考《MSP430x5xx and MSP430x6xx Family User's Guide (Rev. M)——Chapter 11 Digital I/O Module》

1：P1.0 端口翻转

 1 #include <msp430.h>

 2 

 3 int main(void)

 4 {

 5   volatile unsigned int i;

 6 

 7   WDTCTL = WDTPW+WDTHOLD;                   // Stop WDT

 8   P1DIR |= BIT0;                            // P1.0 set as output

 9 

10   while(1)                                  // continuous loop

11   {

12     P1OUT ^= BIT0;                          // XOR P1.0

13     for(i=50000;i>0;i--);                   // Delay

14   }

15 }

注意：为了不影响控制寄存器中其他位的状态，将P1.0端口设置为输出状态选择使用

1  P1DIR |= BIT0;                            // P1.0 set as output

而不是

1  P1DIR = BIT0;                            // P1.0 set as output NO！

2：一个简单的if选择

 1 #include <msp430.h>

 2 

 3 int main(void)

 4 {

 5   WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer

 6   P1DIR |= BIT0;                            // Set P1.0 to output direction

 7 

 8   while (1)                                 // Test P1.4

 9   {

10     if (P1IN & BIT4)

11       P1OUT |= BIT0;                        // if P1.4 set, set P1.0

12     else

13       P1OUT &= ~BIT0;                       // else reset

14   }

15 }

3：P1.4的一个下降沿产生中断，引起P1.0 翻转

 1 #include <msp430.h>

 2 

 3 int main(void)

 4 {

 5   WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer

 6   P1DIR |= BIT0;                            // Set P1.0 to output direction

 7   P1REN |= BIT4;                            // Enable P1.4 internal resistance

 8   P1OUT |= BIT4;                            // Set P1.4 as pull-Up resistance

 9   P1IES |= BIT4;                            // P1.4 Hi/Lo edge

10   P1IFG &= ~BIT4;                           // P1.4 IFG cleared

11   P1IE |= BIT4;                             // P1.4 interrupt enabled

12   

13   __bis_SR_register(LPM4_bits + GIE);       // Enter LPM4 w/interrupt

14   __no_operation();                         // For debugger

15 }

16 

17 // Port 1 interrupt service routine

18 #pragma vector=PORT1_VECTOR

19 __interrupt void Port_1(void)

20 {

21   P1OUT ^= BIT0;                            // P1.0 = toggle

22   P1IFG &= ~BIT4;                          // P1.4 IFG cleared

23 }

4：P1.4上升沿产生中断后使芯片进入LPM（Low Power Model），之后在主程序中翻转P1.0，并改变P1.4的中断触发方式（翻转）

 1 #include <msp430.h>

 2 

 3 int main(void)

 4 {

 5   WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer

 6   P1DIR |= BIT0;                            // Set P1.0 to output direction

 7   P1OUT &= ~BIT0;

 8   P1REN |= BIT4;                            // Enable P1.4 internal resistance

 9   P1OUT |= BIT4;                            // Set P1.4 as pull-Up resistance

10   P1IES &= ~BIT4;                           // P1.4 Lo/Hi edge

11   P1IFG &= ~BIT4;                           // P1.4 IFG cleared

12   P1IE |= BIT4;                             // P1.4 interrupt enabled

13 

14   while(1)

15   {

16     __bis_SR_register(LPM4_bits + GIE);     // Enter LPM4 w/interrupt

17     __no_operation();                        // For debugger

18     P1OUT ^= BIT0;                          // P1.0 = toggle

19     P1IES ^= BIT4;                          // Toggle between H-L and L-H transition triggers

20     P1IE |= BIT4;                           // Enable port interrupt

21   }

22 }

23 

24 // Port 1 interrupt service routine

25 #pragma vector=PORT1_VECTOR

26 __interrupt void Port_1(void)

27 {

28   P1IFG &= ~BIT4;                         // Clear P1.4 IFG

29   P1IE &= ~ BIT4;                         // Clear P1.4 IE

30   _BIC_SR_IRQ(LPM4_bits);                 // Exit LPM4 

31 }

5：对端口PA（P1+P2）进行写操作

 1 #include <msp430.h>

 2 

 3 int main(void)

 4 {

 5   WDTCTL = WDTPW+WDTHOLD;                   // Stop WDT

 6 

 7   PADIR |= 0xFFFF;                          // PA.x output

 8   PAOUT = 0x1234;                           // Write to Port A

 9 

10   __bis_SR_register(LPM4_bits + GIE);       // Enter LPM4 w/interrupts enabled

11   __no_operation();                         // Place BREAKPOINT HERE and check register PAOUT, P1OUT and P2OUT

12 }

说明

1：关于 __bis_SR_register(LPM4_bits + GIE)

　 为了使单片机进入中断，在主函数中必须添加一句__bis_SR_register(LPM4_bits + GIE)"__bis_SR_register (LPM4_bits + GIE)（means go to sleep mode Low_Power_Mode_4 and with General_Interrupt_Enabled.）;其中LPM4_bits可以根据实际情况而改变，而GIE是系统中断使能位，必须置高才有效；而这也是其低能耗的一个重要体现。

2：关于__no_operation();  

Description

__no_operation inserts a NOP opcode into the code stream.

__no_operation is an intrinsic function and produces inline code.

From：this

3：关于__no_operation() and _delay_cycles()

_delay_cycles(xxx) is an intrinsic function that creates code that takes exactly xxx cycles to execute. For a single cycle delay, it would be identical to __no_operation(). You can do a quick test in either IAR or CCS with different values of xxx to see the actual code being created by the __delay_cycles() function. For example:
__delay_cycles(1) creates NOP
__delay_cycles(2) creates JMP  #Next_Address_In_Flash
__delay_cycles(1) creates RLAM.W #3,R15
....

If you only need a single cycle delay, you can stick with __no_operation().

From: this

相关宏定义(in msp430f5529.h)

 1 /************************************************************

 2 * STANDARD BITS

 3 ************************************************************/

 4 

 5 #define BIT0                   (0x0001)

 6 #define BIT1                   (0x0002)

 7 #define BIT2                   (0x0004)

 8 #define BIT3                   (0x0008)

 9 #define BIT4                   (0x0010)

10 #define BIT5                   (0x0020)

11 #define BIT6                   (0x0040)

12 #define BIT7                   (0x0080)

13 #define BIT8                   (0x0100)

14 #define BIT9                   (0x0200)

15 #define BITA                   (0x0400)

16 #define BITB                   (0x0800)

17 #define BITC                   (0x1000)

18 #define BITD                   (0x2000)

19 #define BITE                   (0x4000)

20 #define BITF                   (0x8000)

Steven Meng 

2013.5.22